AIM: To assess whether the presence and width of keratinized mucosa (KM) influence the incidence of peri-implant mucositis and peri-implantitis at the implant level. METHODS: Electronic searches were conducted in MEDLINE/PubMed, Scopus, Embase, and Web of Science, complemented by gray literature and manual searches. Prospective and retrospective cohort studies reporting implant-level incidence of peri-implant diseases in sites with adequate versus inadequate KM were included. Random-effects meta-analyses were performed for two KM thresholds (> 0 mm vs. 0 mm; ≥ 2 mm vs. 0 mm vs. 0 mm: RR = 0.92, 95% CI 0.69-1.21; ≥ 2 mm vs. 0 mm) compared to those without KM (0 mm) (RR = 0.62, 95% CI 0.42-0.91) and in implants with KM ≥ 2 mm compared to < 2 mm (RR = 0.56, 95% CI 0.37-0.84). No significant subgroup differences were observed between prospective and retrospective studies. According to the JBI checklist, 75% of the included studies were classified as having a low risk of bias. CONCLUSION: Evidence from cohort studies suggests no association between KM and peri-implant mucositis incidence, whereas both the presence of KM and a width of ≥ 2 mm are associated with a lower incidence of peri-implantitis. Thus, KM assessment may be considered as a part of peri-implant risk evaluation.
Reis et al. (Thu,) studied this question.